


Ménage À Quatre

by chocolatewithnuts



Category: Undertale (Video Game)
Genre: Established Relationship, F/M, Female Reader, Foursome - F/M/M/M, Give Box & Neo More Love 2K20, Neo is a bit more dominant than the others here NGL, Reader Is Not Frisk (Undertale)
Language: English
Status: Completed
Published: 2020-10-02
Updated: 2020-10-02
Packaged: 2021-03-08 00:27:48
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 4,501
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26766541
Author URL: https://archiveofourown.org/users/chocolatewithnuts/pseuds/chocolatewithnuts
Summary: Alphys makes copies of Mettaton's soul so Box, EX, and Neo can all be present at once. Having three Mettatons in the same room is great news for you.
Relationships: Mettaton (Undertale)/Reader
Comments: 1
Kudos: 24





	Ménage À Quatre

**Author's Note:**

> I'm aware that Mettaton acts the same in canon no matter what form he's in, but I like to imagine that Neo is more dominant and aggressive than the other two. Anyway, happy reading.

You were slumped at your desk, hyperfocused on your work. For a good hour, you were out of tune with the world around you, until you noticed your phone lit up with a notification. You were annoyed by the distraction, but it was also a good opportunity for a much-needed break. Your irritation disappeared when you saw your boyfriend had texted you.

  
  


**Mettaton** : _Hello, darling. Are you free tonight? You better be, because my oh my, do I have a big surprise for you! <3 ;) _

  
  


Knowing Mettaton, the big surprise had to be something sexual. As much as you wanted to tell him you were free, you stopped to think about the logistics of the situation you were in. You were about 75-percent finished with the assignment your boss had given you. It was currently 6PM, and your project was due tomorrow by 8AM sharp. If you said yes to Mettaton, you’d probably have to give up a couple hours of sleep to get the rest of the 25-percent done. The payoff didn’t sound too bad. Your body was screaming for Mettaton’s dick anyway.

You told him you wanted to meet up tonight, and asked him what exactly he had in store for you.

  
  


**Mettaton** : _Well, that’s for me to know and you to find out, sweetheart. ;)_

  
  


You rolled your eyes at how cryptic Mettaton was being, but keeping it a mystery made you even more excited for tonight’s hijinks. You told him you were getting ready now and would let him know when you were leaving.

The sound of shutting your laptop was more satisfying than you had expected it to be. You groomed yourself and dressed up in a manner that was customary for someone who was about to get dicked down. Once you were satisfied with your reflection in the mirror, you informed Mettaton that you were now on your way out.

* * *

Even though you had been there many times already, seeing Mettaton’s mansion still overwhelmed you. It stood there in all its powerful pink glory, one of the biggest symbols of Mettaton’s high status. 

You stopped at the gate where one of his stoic bodyguards stood. He recognized you as Mettaton’s girlfriend, and opened the gates for you. Between the fame and the money, you still couldn’t believe Mettaton loved you enough to welcome a regular person like you into his world. He was sensual and materialistic, and lived a lavish life completely different from yours. But he gave you everything you really needed: a smorgasbord of sensory pleasures to make you forget about the stresses of everyday life—along with lots of laughs and affection. You loved him with your whole heart.

You pulled up into the pink driveway paved with glittery asphalt, and stepped out of your car. Butterflies flew in your stomach as you rang the heart-shaped doorbell. From inside, you could hear Mettaton telling you he was coming in a singsong tone. As soon as he saw you, he took your hand and pulled you inside to avoid paparazzi spying on the two of you from the doorway. After he shut the door, he drank in the sight of you, his eyes already half-lidded with lust.

“Oh, look at you, darling! All dolled up just for me. And in the clothes I bought for you, no less!” he said with a devious smile.

You told him there was no better time to wear the clothes than in front of him. He smirked and led you to his bedroom. Rose petals were scattered on the pink silk sheets, and candles lit on nightstands by both sides of the bed. There was a tray with strawberries and cream resting on the bed, and an array of oils placed by a massage table. What threw you off, however, was the sight of Mettaton’s Box form plugged into the wall, along with another robotic body beside it. The latter resembled Mettaton EX’s humanoid form, but had spikier body parts and flipped up hair. And was that… an arm cannon you saw?

Two water tanks with floating hearts inside stood between the two bodies. The hearts looked exactly like Mettaton’s soul. You furrowed your brows, trying to work out what exactly was going on here.

“You know,” Mettaton began, snapping you out of your thoughts, “as stunning as you look tonight, you also look stressed out, dear. You really need to learn how to take a break. Spending time with me tonight is a great start.”

The same could be said for yourself, you countered. You weren’t reprimanding him so much as you were looking out for him, however. Mettaton was a musician, a model, a businessman, and an actor. He took on many pursuits and could be ruthless about getting them done. There had been times in your relationship where you weren’t able to see him for months because he was too busy rehearsing for this movie, attending that conference, and a whole other slew of this and that’s. It made you all the more grateful you had him all to yourself tonight.

A look of forlorn crossed Mettaton’s face. “You’re right, darling. I suppose I am a bit of a hypocrite for telling you to take it easy. Perhaps we should come to each other more often when we’re stressed out, yes?”

You smiled and nodded, thankful for him looking out for you, along with his desire to spend more time with you.

He gave you a grin so sweet, your heart could burst. “Now then, onto the surprise…” he began sashaying over to his box body and the one you couldn’t identify. “Well, you see, I planned out an action movie that would feature all three of my bodies: Box, EX, and Neo. I never made Neo public because he was built specifically to hunt humans. Revealing him would've been terrible for my reputation among humans, even though his combat features have already been removed. But I’m bringing him out to the public eye now, because I figured he would be perfect for a movie that’s more gory than usual.”

“So a couple weeks ago, I asked Dr. Alphys if there was a way to have all three of my bodies present at the same time. I know I could’ve had the production team add in CGI’s of my Box and Neo forms, but I could get away with a cheaper budget if both of those bodies could act alongside my EX form.”

“So Alphys created temporary duplicates of my soul. On average, they last about four hours before they dissolve—more or less depending on how much energy I exert. They’ve worked very well, and I’ve been able to get in plenty of shots for my movie. Though that’s most likely due to my excellent time management.”

Mettaton paused, allowing you to let all of this information sink in. After a few seconds, he spoke again, a devilish grin forming on his face. “And just a couple of hours ago, I realized something interesting…”

He began strutting towards you, and you couldn’t help fixating on the sway of his hips. As soon as he was in front of you, he took hold of your hands and looked into your eyes.

“I realized I have a girlfriend who’s always eager to experiment with me in bed. I bet she’d love it if my Box and Neo bodies had temporary souls, so she can have a foursome with all of my forms.”

Your eyes widened as a chill ran down your spine. You looked over at Box and Neo, who were both plugged into the wall. They were stationary right now, with Box’s wheel tucked away and Neo’s eyes shut as his face pointed down. You imagined how they’d pleasure you when they were powered on: Box’s fingers pumping inside you as Neo made you eat his heart out. The thought went straight to your crotch, and you readily agreed to Mettaton’s offer.

Mettaton smiled and squeezed your hands. “I knew you’d be excited about this, darling. Now, I want you to undress and lie face down on the massage table; it’s my duty to take my time with you and help you destress tonight. I’ll have my Box form start you off with a massage while you and I indulge in strawberries and whipped cream. You’re a lovely woman, but you don’t have the posture to match it. Lucky for you, you’ve got a boyfriend with hands that’d make even the most skilled masseuse jealous.”

You rolled your eyes, and he laughed at you with a wink. He knew you secretly loved his ego.

As you undressed, Mettaton kneeled down and took a heart out of the tank, putting it inside his box body. You lied down on your stomach and watched as Box powered on, his screen lighting up as his wheel emerged from the bottom of his body. He also let out his deep and infamous “oh, yes!” You didn’t know whether to laugh or shake your head. You opted for both.

Box wheeled over towards you as EX went to the bed to get the strawberries and whipped cream.

“HEY, DARLING,” Box began as he grabbed a bottle of massage oil. “WANNA KNOW WHAT’S BETTER THAN METTATON?”

EX kneeled in front of you as he set down the bowls of strawberries and cream with a smile. You looked between him and Box. Two Mettatons, you guessed.

“THAT’S RIGHT! NOW CAN YOU GUESS WHAT YOUR PRIZE IS FOR ANSWERING CORRECTLY?”

More questions, you said.

“THAT’S NOT THE FULL ANSWER, BUT I’LL GIVE YOU PARTIAL CREDIT FOR THAT ONE. THE OTHER PART OF THE ANSWER IS A DEEP TISSUE MASSAGE FROM METTATON AND HIS STURDY, MASCULINE HANDS,” he said as he began pouring a generous amount of oil on your back.

Those sturdy, masculine hands were also attached to cartoony, noodle-like arms, you added with a snicker.

“YOU BRING UP MY EXTENDABLE ARMS AS THOUGH THEY’RE A BAD THING. I’LL HAVE YOU KNOW THEY’VE HELPED MANY PEOPLE OF VARYING HEIGHTS REACH ITEMS FROM THE TOP SHELF,” he replied in a playfully defensive tone.

You were just messing with him, you told him even though he already knew that, and you love every part of him no matter what form he was in.

“OF COURSE YOU DO, DARLING. I’M IRRESISTIBLE NO MATTER WHAT,” Box said before he finally brought his sturdy, masculine hands to your shoulders. He began kneading at them, and you could already feel the stress from the past week washing away.

You rested your chin on your hands, watching as EX fiddled with the dials on his chassis. A few seconds later, sensual music from his latest album played from his speakers. You asked him how much more egotistical he could get.

He decided to answer your rhetorical question as he dipped a strawberry in whipped cream. “Well, I could fuck my Neo form in front of you,” he said, pressing the fruit between your lips. “But I want tonight to be all about you.”

You took a bite and licked the cream from your lips after swallowing. That would take a whole new meaning to the phrase ‘go fuck yourself’, you said.

He laughed smugly. “That would certainly be something, wouldn’t it? And you’d be the only one lucky enough to watch it.”

You and EX kept eating strawberries and cream as Box worked at the knots in your back. At some points, EX would kiss you before you could lick the whipped cream off your lips. You’d melt into his kiss, moaning gently at the feeling of his soft lips and Box getting rid of the tension from your body.

The bowls of strawberries and cream were soon finished off, and you and EX focused on making out. His kisses grew more feverish as Box’s hands snaked lower down your body, now kneading your ass. His motions were right on the borderline of still massaging and copping a feel, until his fingers reached down to rub your clit. His touch sent a shock through your body, and you threw your arms around EX to kiss him deeper. You sucked his lower lip and moaned at the feeling of Box’s ministrations.

You soon pulled away from the kiss to catch your breath, and Box used this as an opportunity to carry you over to the bed. He set you down on your back and resumed working at your clit, turning on his vibrating fingers. You gasped as you grabbed at the sheets, your jaw slack as you locked eyes with EX. He licked his lips as he watched the scene unfold in front of him, his eyes hazy.

“I think it’s time to power up Neo,” he offered. “What do you think, darling?”

You bit your lip and nodded. Box’s lights formed into a heart shape as you continuously came undone under his touch.

As EX inserted the temporary soul inside Neo, you couldn’t help but briefly wonder if Box could even feel anything. You’d have to ask later when you’re not writhing underneath his hand. Despite yourself, you leaned over and pressed a kiss to his lights. For that, he turned up the speed of his vibrations, and you shut your eyes and moaned louder against him.

Your head snapped up as the sound of another “oh, yes!” boomed throughout the room as Neo booted up. You didn’t have it in you to laugh or roll your eyes this time; Box was making you feel too weak. With his other hand, he prodded at your entrance.

“MY, MY, YOU’RE SOAKING WET, DARLING! WAS IT FROM MY VIBRATIONS, OR NEO’S ‘OH, YES’?”

You moaned out a shaky ‘shut up’, tugging on the silk sheets as Box inserted his fingers inside you. You lied back on the bed, rocking your hips upwards as his fingers vibrated against and moved inside you. EX and Neo approached you, lying on the bed on either side of you. 

You were amazed by Neo’s build. He was taller than EX, his legs hanging long over the bed. His body looked more industrious and sturdy as well, so you assumed this was the form that consumed the most energy.

EX took one of your hands, wrapping it in both of yours. “Sweetheart, let me remind you that Neo isn’t dangerous anymore; his anti-human combat features were removed a long time ago. So you don't need to worry about him pointing his cannon at your head or anything.”

Before you realized it, you frowned. You thought it was subtle, but it apparently was not lost on EX. His pretty face twisted in bewilderment. “Hold on a second. Would you actually be into that?”

Your face reddened as you smiled sheepishly, nodding a little. Neo could do it while you were getting fucked, you suggested. Well, you certainly learned something new about yourself today.

He chuckled. “Very well then, dear. But his cannon isn’t loaded, so hopefully that doesn’t ruin the eroticism.”

You smirked, then grabbed at Neo’s cannon arm as Box pumped his fingers inside you faster. Neo gripped onto your arm tightly—more so than EX would during sex. Neo seemed even more firm and dominant than the other forms.

EX and Neo brought their lips to your breasts, mouthing at your nipples. You could feel Neo’s sharp teeth between the bud, making you wince in pleasure. Meanwhile, EX was more gentle as he held your hand, rubbing your thumb with his as he licked your nipple. Between Neo’s dominance, EX’s tenderness, and Box fingerfucking you, you were on the brink of orgasm—that is, until Neo slapped Box’s hands away from you.

“We can’t let this pillow princess cum just yet,” Neo scoffed. “She hasn’t earned it.”

“Oh, but Neo-darling, tonight is supposed to be all about her,” EX rebutted.

You put your hands between the two of them. You told EX that he was right, tonight was all about what you wanted. And part of what you wanted was to pleasure Neo.

Neo laughed derisively at EX. “See? Our girlfriend’s a responsible woman, she works hard to get what she wants. She’s a good little whore.”

With that, Neo positioned you so that you were sitting up on the edge of the bed. He stood up and got off of it so he was standing in front of you. His heart case was at your eye level, dripping with pink goo. You watched as Neo opened up the container, taking out his soul and thrusting it in your hands. It burned a little under your skin, as goo seeped out from between the spaces of your fingers.

“Don’t just stare at it. Lick it. You have to get me off to earn your orgasm,” Neo commanded.

You looked up at him with wide eyes and nodded. “Yes, sir.”

You wanted to tease him with slow, light licks, but Neo was all business and you didn’t want to upset him. But at the same time, you’d love to have him punish you for not giving him exactly what he wanted.

So you did just that. You kept your eyes on him as you gently ran the tip of your tongue over his heart, holding onto his strong metallic thighs. His face twisted into an intimidating, yet handsome snarl that made your stomach jump in a disturbingly pleasant way.

“I didn’t tell you to tease me, you little slut. You better get straight to business, or else…” 

He took his cannon arm, and propped the barrel against the side of your head, “You’ll get it.”

“OH MY. THIS IS SUPPOSED TO BE A FAMILY FRIENDLY SHOW,” Box called out sarcastically as his hands flew to either side of his head in shock.

You glared at him for interfering with the mood, but still had to bite back a laugh. At any other time, you would’ve called Box a hypocrite for saying that when he once posed seductively on the beach in a bikini during a G-rated movie. But right now, you were too turned on by the threat of (non-existing) danger with Neo’s (unloaded) cannon against your head. 

You maintained eye contact with him as you kissed and sucked on his heart, eager for his approval. His gaze was cold and piercing as he used his other hand to tug at your hair. You whimpered, savoring the taste of hot artificial strawberries against your tongue.

EX came next to Neo, looking down at you with a proud smile. “I can tell you’re doing such a fabulous job, darling. Why don’t you tell her that, Neo? She loves being praised.”

Neo schooled his expression to be neutral as he stared down at you. At that, you licked his heart more urgently, hoping to get something out of him, anything.

“I guess you’re right,” he admitted. “She’s clearly had a lot of practice with you. Why don’t you fuck her while she finishes me off?”

EX smirked. “Gladly,” he purred, gazing at you again. “Make yourself comfortable on the bed, sweetheart. Box and I will take good care of you while you work on Neo.”

God, this was going to be the best case of sensory overload you’d ever had. You pulled your lips away from Neo’s soul, licking the goo off your lips before propping yourself on the bed once more. You laid down and began working at Neo’s heart again as Box and EX approached you.

EX fiddled with a couple dials on his body before the plates on his crotch slid open to reveal a grey metal dildo with a pink tip and heart-shaped ridges. You’d roll your eyes and call it camp if it hadn’t brought you to orgasm countless times before.

EX spread your legs and licked his lips before looking into your eyes. “Are you ready, my love?”

You emitted a muffled, yet excited ‘mhmm’ against Neo’s heart. You shut your eyes as EX pressed his cock against your entrance, whimpering as he eased inside you.

“There you go, dear, that’s a good girl,” he assured you as he stroked his hand through your hair.

While gaining a steady rhythm, Box pressed a silken glove against your clit. He turned on the vibrating function on his fingers again, choosing the slowest speed to start with. You writhed against his hand, feeling a small, pleasant tingle.

Your ministrations against Neo’s heart had unintentionally slowed to match Box and EX’s pace. Neo came over and grabbed your jaw, his gaze icier than usual.

“I didn’t tell you to slow down, did I?” he scowled.

“N-no, sir,” you said, staring up at him in lecherous fear. You picked up the pace and he grunted, closing his eyes. His hand fell from your jaw and down to your breast, idly fondling it. 

The image of Neo’s O face burned into your mind. You looked between him, EX’s focused expression as he thrusted inside you, and the lights on Box’s screen. Against the yellow background, red pixels moved across the screen with the phrase ‘I <3 U’. Your heart felt like it was about to burst. You moved Neo’s heart to one hand as you used the other to lace your fingers with Box’s.

“A little faster, darling?” EX asked above you through shaky breaths.

You nodded enthusiastically as your tongue continued working against Neo’s soul. EX thrusted faster inside you as the vibrations of Box’s fingers sped up. You gasped and suppressed your loud moans against Neo’s heart, squeezing Box’s hand tighter.

“Th-that’s my girl,” EX praised, his voice becoming glitchy. “Al-always taking my cock like a champ—”

He gripped onto your sides, digging his fingers into your skin. Box’s fingers continued to move in jittery circles against your clit while Neo squeezed your tits. You suckled on Neo’s heart along different areas, which seemed to make him tick the most.

“F-fuck yeah,” you heard him groan from above you.

EX and Neo’s moans were music to your ears, but you wanted to hear them louder and more urgent. You let go of Box’s hand to grab EX’s ass, manipulating his pace so he could go faster.

He chuckled playfully. “My, my, you really are a slutty one tonight, aren’t you? With three of me around, I can’t blame you, darling.”

He began thrusting even faster inside you as you kept your hand on his squishy ass. His moans turned more erratic while Box turned the vibrations to the highest speed, circling his fingers quickly against you. You whimpered loudly as you smashed your lips against Neo’s heart, suckling on it so hard your cheekbones hallowed. You heard a small gasp come out of him while he doubled over and gripped your arm firmly.

You felt open, fucked, and full. You wrapped your legs around EX’s enviously slim waist, urging him even closer to you. You were on the edge, and the feeling of EX releasing inside you pushed you over it. He moaned erratically right by your ear as you both came, and you kissed Neo’s heart feverishly to ensure he would cum too. Within moments, Neo joined the chorus of moans and had a death grip on your arm, his voice gruffer than the rest.

What brought you down from your high was the feeling of Neo’s heart dissolving on your hand, all the goo dripping down. Neo’s body collapsed with a loud ‘clank!’ on the floor. You were about to panic and feel guilty about literally fucking him to death, until you remembered the soul was a short-term duplicate.

Before relief could sink in, you heard the sound of EX booting down: a slow, low-pitched version of his “oh, yes!”. You quickly rolled out of the way before his heavy metal body could crush you. His body fell to the bed, bouncing a couple times from the hard impact. You looked at the scene in front of you: two of your robot boyfriend’s bodies lying face down on the floor and bed, all out of battery because of you. You then glanced over at Box Mettaton, who was still powered on with a smirking face on his lights.

“EX AND NEO ARE DOWN. I’M THE LONE SURVIVOR. THIS BODY USES THE LEAST AMOUNT OF POWER, SO I WIN. PROUD OF ME, DARLING?"

You chuckled and reminded him he was currently running on a temporary duplicate of his soul. You then asked him if he knew how much longer his box body had left.

“I’D SAY ABOUT AN HOUR, GIVE OR TAKE,” he replied. “THAT SHOULD BE ENOUGH TIME FOR YOU TO RELAX AND GET YOURSELF CLEANED UP. MEANWHILE, I’M GOING TO CHARGE MY EX BODY.”

You nodded and headed over to the closet, where you grabbed a change of clothes. Considering your active sex life with Mettaton, you knew keeping a few outfits in his suite would be a smart idea. You went to the bathroom to clean up and take a shower, before coming back to see that Box Mettaton had powered down. So much for that one hour left. Those vibrator fingers must have used up a lot of battery.

EX was lying down on the bed, his charger plugged into the wall. He was powered back on now, smiling softly as he saw you. You remembered that project you had due early in the morning tomorrow. You glanced over at the clock, seeing it was almost 9PM. Fuck it, you’d rather spend the night with your boyfriend. You could just leave before sunrise and finish everything up a couple hours before the deadline. If you left by 5AM, you could get back home by 5:30, maybe even earlier because traffic is light early in the morning and then you’d have just over two hours to—

“Oh, I know that look,” Mettaton piped in. “You’re thinking too hard again. About work, I bet.”

Your eyes widened like a deer caught in the headlights, his voice snapping you out of our thoughts. You sighed and said yes, a bit annoyed that he could read you like a book. But it proved just how close you were, all the same.

“Like I said earlier, darling, tonight is all about de-stressing. Don’t go back home to your wretched desk just yet, spend the night with me!”

You smiled and agreed, telling him you were thinking of that anyway. You got under the covers with him, and placed a pillow on top of his chassis so you could comfortably rest your head against him. Mettaton held you close, and told you that although he was perfect, he sometimes found himself envying how soft and fleshy humans were. You reassured him by listing all the advantages he had with a body made of metal: extendable arms that could reach inhumanly high shelves, the ability to keep your girlfriend warm during winter, the inability to get sick, and most importantly of all…

Having multi-speed vibrators for fingers.

**Author's Note:**

> Yes, I think EX has a squishy ass. It probably feels like one of those gel wrist rests on mouse pads.
> 
> Anyway, this fic was just something quick and self-indulgent. I regret nothing. See you all in Hell.


End file.
